When configuring the PureMessage Block List/Allow List, you get a 'Microsoft .NET Framework' error similar to the following:
Unhandled exception has occurred in a component in your application, if you click Continue, the application will ignore this error and attempt to continue.
Item has already been added. Key in dictionary: '*@domainname.com' Key being added '*@domainname.com'
Sophos product and version
PureMessage for Microsoft Exchange 3.0.1
Windows 2003 SP2
What to do
The error dialog box usually displays the email address that is causing the issue. Please note this down.
If you have a configuration that you created and saved previously, you can import this and base your new configuration on it.